WO 2009/050003 A1 discloses a heat pump dryer whose heat exchanger is cleaned from lint using rinsing liquid. The rinsing liquid is condensed water stored in a rinse container within a removable condensate reservoir. The condensate is pumped from a condensate collecting device to the removable condensate reservoir by a pumping and feeding arrangement having a pump and a valve. The pump and the valve are controlled by a control unit. The valve comprises two outlets—one outlet for connecting an internal line and a second outlet for connecting a draining line. The internal line is fluidly connected to the removable condensate reservoir. The draining line is fluidly connectable to an external waste water system, if existing. After rinsing the heat exchanger, the remaining rinsing liquid and stored condensate can be guided by the draining line into the external waste water system. Thus, a manual exhausting the removable condensate reservoir is avoided. If said external waste water system does not exist, the draining line has no function. The preconditions for using this known draining line are: connecting the draining line to an external waste water system, external sink or the like, and manually operating an operation unit serving as an input panel to the control unit. Depending on the manual operation of said operation unit the pumping and feeding arrangement is capable to pump the condensate from the condensate collecting device selectively through the internal line to the rinse container of the removable condensate reservoir (during the rinsing process) and through the draining line to the external waste water system (after the rinsing process).